Delirium Diagnosis Using the Confusion Assessment Method

Core Diagnostic Algorithm

The Confusion Assessment Method (CAM) is a validated diagnostic instrument that enables trained healthcare professionals to rapidly identify delirium in less than 5 minutes using a four-feature algorithm based on DSM criteria, as recommended by the American College of Cardiology 1, 2
The CAM diagnostic algorithm requires the presence of all of the following: Feature 1 (Acute onset and fluctuating course) and Feature 2 (Inattention), and either Feature 3 (Disorganized thinking) or Feature 4 (Altered level of consciousness) 2, 3, 4

The CAM demonstrates strong psychometric properties with a sensitivity of 82-100% (pooled meta-analysis: 82%, 95% CI: 69-91%) and a specificity of 89-99% (pooled meta-analysis: 99%, 95% CI: 87-100%) 2

The CAM should be administered by trained healthcare staff as part of a comprehensive assessment that includes brief cognitive testing, attention testing, and information from a knowledgeable informant about baseline cognitive function and acute changes 1, 2, 3

The CAM-ICU is designed specifically for intensive care unit patients with very good psychometric properties, as recommended by the American College of Radiology 5, 6
The B-CAM is a brief CAM variant for rapid screening, and the Short CAM is an abbreviated version with an available training manual 2, 3, 5, 6

Delirium screening should occur at least once per nursing shift (every 8-12 hours) given the fluctuating nature of delirium symptoms, as recommended by the JAMA Surgery 8

Hypoactive delirium is frequently missed by clinical teams despite being the most common subtype, particularly in cancer patients and older adults, and the CAM performs optimally when used for screening rather than as the sole diagnostic criterion 1, 2, 3, 7